The present invention relates to a data storage device and a method of controlling write of user data thereof, and more particularly to judgment about approval or disapproval of write of user data to a medium.
Devices using various types of media such as optical disks, magnetic tapes and semiconductor circuits are known as data storage devices. Among them, hard disk drives (HDDs) have become popular as storage devices for computers to such an extent that they are one type of the storage devices indispensable for today's computers. Further, not limited to computers, their application is widening more and more due to the superior characteristics with the advent of moving picture recording/reproducing devices, car navigation systems, mobile phones, and removable memories used in digital cameras and the like.
A magnetic disk used in the HDD using a servo sector system has a plurality of data tracks which are concentrically formed. A plurality of servo data having address information, and a plurality of data sectors containing user data are recorded in each data track. A plurality of data sectors are recorded between the servo data. A head element supported by a swinging actuator accesses a desired data sector in accordance with the address information of the servo data, whereby data can be written to the data sector and the data can be read out from the data sector.
When in the HDD using the sector servo system as described above, a target data track is sought to access the target data sector, mechanical vibration remains in the actuator in some cases. This vibration is mainly caused by mechanical resonance of the actuator. When a frequency of this residual vibration takes a value near a sampling frequency, the HDD cannot detect this vibration and positional shift of the head element accompanied by this vibration by using a servo signal. If data is written to a magnetic disk in a state in which the actuator and the head element vibrate, a probability is high in which off-track write is present.
Then, for example, Patent Document 1 (Japanese Patent Laid-open No. 2003-338146) discloses a technique in which in the case where a signal in an off-track detection area which exists not in a servo area but in a data area is read and a level of a regenerative output of the signal concerned drops to a level equal to or lower than a threshold when data is recorded in the data area, it is judged that off-track has been generated, and thus the data recording is stopped. In the technique disclosed in Patent Document 1, when the data is written to the magnetic disk device, off-track detection signal previously recorded in an off-track detection area existing between the servo area and the servo area is read out with a read head, and it is determined whether or not the output level of the off-track detection signal exceeds a threshold in order to judge the presence or absence of the off-track.